In-Place Transposition of Rectangular Matrices

Abstract

We present a new Algorithm for In-Place Rectangular Transposition of an m by n matrix A that is efficient. In worst case it is O(N logN) where N = mn. It uses a bit-vector of size IWORK words to further increase its efficiency. When IWORK=0 no extra storage is used. We also review some of the other existing algorithms for this problem. These contributions were made by Gower, Windley, Knuth, Macleod, Laffin and Brebner (ACM Alg. 380), Brenner (ACM Alg. 467), and Cate and Twigg (ACM Alg. 513). Performance results are given and they are compared to an Out-of-Place Transposition algorithm as well as ACM Algorithm 467.